Sequence transmission for sidelink communications

ABSTRACT

Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment may generate a pseudorandom noise (PN) sequence, modulate the PN sequence based at least in part on a modulation order parameter, and transmit the PN sequence in one or more symbols prior to transmitting sidelink data. The one or more symbols used to transmit the PN sequence may be used for automatic gain control (AGC) training at a receiving device. The user equipment may then transmit the sidelink data in a plurality of symbols that are subsequent in time relative to the one or more symbols used to transmit the PN sequence, and the receiving device may process the sidelink data based on the AGC training. Numerous other aspects are provided.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.16/828,491, filed Mar. 24, 2022, entitled “SEQUENCE TRANSMISSION FORSIDELINK COMMUNICATIONS,” which claims priority to U.S. ProvisionalPatent Application No. 62/858,665, filed on Jun. 7, 2019, entitled“SEQUENCE TRANSMISSION FOR SIDELINK COMMUNICATIONS,” the contents ofwhich are incorporated herein by reference in their entireties.

FIELD OF THE DISCLOSURE

Aspects of the present disclosure generally relate to wirelesscommunication and to techniques and apparatuses for sequencetransmission for sidelink communications.

BACKGROUND

Wireless communication systems are widely deployed to provide varioustelecommunication services such as telephony, video, data, messaging,and broadcasts. Typical wireless communication systems may employmultiple-access technologies capable of supporting communication withmultiple users by sharing available system resources (e.g., bandwidth,transmit power, and/or the like). Examples of such multiple-accesstechnologies include code division multiple access (CDMA) systems, timedivision multiple access (TDMA) systems, frequency-division multipleaccess (FDMA) systems, orthogonal frequency-division multiple access(OFDMA) systems, single-carrier frequency-division multiple access(SC-FDMA) systems, time division synchronous code division multipleaccess (TD-SCDMA) systems, and Long Term Evolution (LTE).LTE/LTE-Advanced is a set of enhancements to the Universal MobileTelecommunications System (UMTS) mobile standard promulgated by theThird Generation Partnership Project (3GPP).

A wireless communication network may include a number of base stations(BSs) that can support communication for a number of user equipment(UEs). A user equipment (UE) may communicate with a base station (BS)via the downlink and uplink. The downlink (or forward link) refers tothe communication link from the BS to the UE, and the uplink (or reverselink) refers to the communication link from the UE to the BS. As will bedescribed in more detail herein, a BS may be referred to as a Node B, agNB, an access point (AP), a radio head, a transmit receive point (TRP),a New Radio (NR) BS, a 5G Node B, and/or the like.

The above multiple access technologies have been adopted in varioustelecommunication standards to provide a common protocol that enablesdifferent user equipment to communicate on a municipal, national,regional, and even global level. New Radio (NR), which may also bereferred to as 5G, is a set of enhancements to the LTE mobile standardpromulgated by the Third Generation Partnership Project (3GPP). NR isdesigned to better support mobile broadband Internet access by improvingspectral efficiency, lowering costs, improving services, making use ofnew spectrum, and better integrating with other open standards usingorthogonal frequency division multiplexing (OFDM) with a cyclic prefix(CP) (CP-OFDM) on the downlink (DL), using CP-OFDM and/or SC-FDM (e.g.,also known as discrete Fourier transform spread OFDM (DFT-s-OFDM)) onthe uplink (UL), as well as supporting beamforming, multiple-inputmultiple-output (MIMO) antenna technology, and carrier aggregation.However, as the demand for mobile broadband access continues toincrease, there exists a need for further improvements in LTE and NRtechnologies. Preferably, these improvements should be applicable toother multiple access technologies and the telecommunication standardsthat employ these technologies.

SUMMARY

In some aspects, a method of wireless communication, performed by a userequipment (UE), may include generating a pseudorandom noise (PN)sequence; modulating the PN sequence based at least in part on amodulation order parameter; transmitting the PN sequence in one or moresymbols prior to transmitting sidelink data; and transmitting thesidelink data in a plurality of symbols that are subsequent in timerelative to the one or more symbols used to transmit the PN sequence.

In some aspects, a method of wireless communication, performed by a UE,may include receiving one or more automatic gain control (AGC) symbolscarrying a modulated PN sequence in one or more symbols prior toreceiving sidelink data; configuring a gain for one or more receivecomponents based on one or more signal characteristics associated withthe one or more AGC symbols; receiving the sidelink data in a pluralityof symbols that are subsequent in time relative to the one or moresymbols in which the one or more AGC symbols carrying the modulated PNsequence are received; and applying the configured gain to process thesidelink data.

In some aspects, a UE for wireless communication may include a memoryand one or more processors operatively coupled to the memory. The memoryand the one or more processors may be configured to generate a PNsequence; modulate the PN sequence based at least in part on amodulation order parameter; transmit the PN sequence in one or moresymbols prior to transmitting sidelink data; and transmit the sidelinkdata in a plurality of symbols that are subsequent in time relative tothe one or more symbols used to transmit the PN sequence.

In some aspects, a UE for wireless communication may include a memoryand one or more processors operatively coupled to the memory. The memoryand the one or more processors may be configured to receive one or moreAGC symbols carrying a modulated PN sequence in one or more symbolsprior to receiving sidelink data; configure a gain for one or morereceive components based on one or more signal characteristicsassociated with the one or more AGC symbols; receive the sidelink datain a plurality of symbols that are subsequent in time relative to theone or more symbols in which the one or more AGC symbols carrying themodulated PN sequence are received; and apply the configured gain toprocess the sidelink data.

In some aspects, a non-transitory computer-readable medium may store oneor more instructions for wireless communication. The one or moreinstructions, when executed by one or more processors, may cause the oneor more processors to: generate a PN sequence; modulate the PN sequencebased at least in part on a modulation order parameter; transmit the PNsequence in one or more symbols prior to transmitting sidelink data; andtransmit the sidelink data in a plurality of symbols that are subsequentin time relative to the one or more symbols used to transmit the PNsequence.

In some aspects, a non-transitory computer-readable medium may store oneor more instructions for wireless communication. The one or moreinstructions, when executed by one or more processors, may cause the oneor more processors to: receive one or more AGC symbols carrying amodulated PN sequence in one or more symbols prior to receiving sidelinkdata; configure a gain for one or more receive components based on oneor more signal characteristics associated with the one or more AGCsymbols; receive the sidelink data in a plurality of symbols that aresubsequent in time relative to the one or more symbols in which the oneor more AGC symbols carrying the modulated PN sequence are received; andapply the configured gain to process the sidelink data.

In some aspects, an apparatus for wireless communication may includemeans for generating a PN sequence; means for modulating the PN sequencebased at least in part on a modulation order parameter; means fortransmitting the PN sequence in one or more symbols prior totransmitting sidelink data; and means for transmitting the sidelink datain a plurality of symbols that are subsequent in time relative to theone or more symbols used to transmit the PN sequence.

In some aspects, an apparatus for wireless communication may includemeans for receiving one or more AGC symbols carrying a modulated PNsequence in one or more symbols prior to receiving sidelink data; meansfor configuring a gain for one or more receive components based on oneor more signal characteristics associated with the one or more AGCsymbols; means for receiving the sidelink data in a plurality of symbolsthat are subsequent in time relative to the one or more symbols in whichthe one or more AGC symbols carrying the modulated PN sequence arereceived; and means for applying the configured gain to process thesidelink data.

Aspects generally include a method, apparatus, system, computer programproduct, non-transitory computer-readable medium, user equipment, basestation, wireless communication device, and processing system assubstantially described herein with reference to and as illustrated bythe accompanying drawings and specification.

The foregoing has outlined rather broadly the features and technicaladvantages of examples according to the disclosure in order that thedetailed description that follows may be better understood. Additionalfeatures and advantages will be described hereinafter. The conceptionand specific examples disclosed may be readily utilized as a basis formodifying or designing other structures for carrying out the samepurposes of the present disclosure. Such equivalent constructions do notdepart from the scope of the appended claims. Characteristics of theconcepts disclosed herein, both their organization and method ofoperation, together with associated advantages will be better understoodfrom the following description when considered in connection with theaccompanying figures. Each of the figures is provided for the purposesof illustration and description, and not as a definition of the limitsof the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the above-recited features of the present disclosure can beunderstood in detail, a more particular description, briefly summarizedabove, may be had by reference to aspects, some of which are illustratedin the appended drawings. It is to be noted, however, that the appendeddrawings illustrate only certain typical aspects of this disclosure andare therefore not to be considered limiting of its scope, for thedescription may admit to other equally effective aspects. The samereference numbers in different drawings may identify the same or similarelements.

FIG. 1 is a block diagram conceptually illustrating an example of awireless communication network, in accordance with various aspects ofthe present disclosure.

FIG. 2 is a block diagram conceptually illustrating an example of a basestation in communication with a UE in a wireless communication network,in accordance with various aspects of the present disclosure.

FIG. 3 is a block diagram conceptually illustrating an example of aframe structure in a wireless communication network, in accordance withvarious aspects of the present disclosure.

FIG. 4 is a block diagram conceptually illustrating an example slotformat with a normal cyclic prefix, in accordance with various aspectsof the present disclosure.

FIG. 5 is a block diagram illustrating an example sequence transmissionfor sidelink communications, in accordance with various aspects of thepresent disclosure.

FIG. 6 is a block diagram illustrating an example slot structure for asingle-slot transmission of a sequence for sidelink communications, inaccordance with various aspects of the present disclosure.

FIG. 7 is a block diagram illustrating an example slot structure formulti-slot transmissions of a sequence for sidelink communications, inaccordance with various aspects of the present disclosure.

FIG. 8 is a block diagram illustrating an example slot structure fortransmitting a sequence for sidelink communications in multiple symbols,in accordance with various aspects of the present disclosure.

FIG. 9 is a block diagram illustrating an example resource elementmapping for transmitting a sequence for sidelink communications, inaccordance with various aspects of the present disclosure.

FIGS. 10 and 11 are diagrams illustrating example processes relating tosequence transmission for sidelink communications, in accordance withvarious aspects of the present disclosure.

DETAILED DESCRIPTION

Various aspects of the disclosure are described more fully hereinafterwith reference to the accompanying drawings. This disclosure may,however, be embodied in many different forms and should not be construedas limited to any specific structure or function presented throughoutthis disclosure. Rather, these aspects are provided so that thisdisclosure will be thorough and complete, and will fully convey thescope of the disclosure to those skilled in the art. Based on theteachings herein one skilled in the art should appreciate that the scopeof the disclosure is intended to cover any aspect of the disclosuredisclosed herein, whether implemented independently of or combined withany other aspect of the disclosure. For example, an apparatus may beimplemented or a method may be practiced using any number of the aspectsset forth herein. In addition, the scope of the disclosure is intendedto cover such an apparatus or method which is practiced using otherstructure, functionality, or structure and functionality in addition toor other than the various aspects of the disclosure set forth herein. Itshould be understood that any aspect of the disclosure disclosed hereinmay be embodied by one or more elements of a claim.

Several aspects of telecommunication systems will now be presented withreference to various apparatuses and techniques. These apparatuses andtechniques will be described in the following detailed description andillustrated in the accompanying drawings by various blocks, modules,components, circuits, steps, processes, algorithms, and/or the like(collectively referred to as “elements”). These elements may beimplemented using hardware, software, or combinations thereof. Whethersuch elements are implemented as hardware or software depends upon theparticular application and design constraints imposed on the overallsystem.

It should be noted that while aspects may be described herein usingterminology commonly associated with 3G and/or 4G wireless technologies,aspects of the present disclosure can be applied in othergeneration-based communication systems, such as 5G and later, includingNR technologies.

FIG. 1 is a diagram illustrating a wireless network 100 in which aspectsof the present disclosure may be practiced. The wireless network 100 maybe an LTE network or some other wireless network, such as a 5G or NRnetwork. The wireless network 100 may include a number of BSs 110 (shownas BS 110 a, BS 110 b, BS 110 c, and BS 110 d) and other networkentities. A BS is an entity that communicates with user equipment (UEs)and may also be referred to as a base station, a NR BS, a Node B, a gNB,a 5G node B (NB), an access point, a transmit receive point (TRP),and/or the like. Each BS may provide communication coverage for aparticular geographic area. In 3GPP, the term “cell” can refer to acoverage area of a BS and/or a BS subsystem serving this coverage area,depending on the context in which the term is used.

A BS may provide communication coverage for a macro cell, a pico cell, afemto cell, and/or another type of cell. A macro cell may cover arelatively large geographic area (e.g., several kilometers in radius)and may allow unrestricted access by UEs with service subscription. Apico cell may cover a relatively small geographic area and may allowunrestricted access by UEs with service subscription. A femto cell maycover a relatively small geographic area (e.g., a home) and may allowrestricted access by UEs having association with the femto cell (e.g.,UEs in a closed subscriber group (CSG)). A BS for a macro cell may bereferred to as a macro BS. A BS for a pico cell may be referred to as apico BS. A BS for a femto cell may be referred to as a femto BS or ahome BS. In the example shown in FIG. 1, a BS 110 a may be a macro BSfor a macro cell 102 a, a BS 110 b may be a pico BS for a pico cell 102b, and a BS 1110 c may be a femto BS for a femto cell 102 c. A BS maysupport one or multiple (e.g., three) cells. The terms “eNB”, “basestation”, “NR BS”, “gNB”, “TRP”, “AP”, “node B”, “5G NB”, and “cell” maybe used interchangeably herein.

In some aspects, a cell may not necessarily be stationary, and thegeographic area of the cell may move according to the location of amobile BS. In some aspects, the BSs may be interconnected to one anotherand/or to one or more other BSs or network nodes (not shown) in thewireless network 100 through various types of backhaul interfaces suchas a direct physical connection, a virtual network, and/or the likeusing any suitable transport network.

Wireless network 100 may also include relay stations. A relay station isan entity that can receive a transmission of data from an upstreamstation (e.g., a BS or a UE) and send a transmission of the data to adownstream station (e.g., a UE or a BS). A relay station may also be aUE that can relay transmissions for other UEs. In the example shown inFIG. 1, a relay station 110 d may communicate with macro BS 110 a and aUE 120 d in order to facilitate communication between BS 110 a and UE120 d. A relay station may also be referred to as a relay BS, a relaybase station, a relay, and/or the like.

Wireless network 100 may be a heterogeneous network that includes BSs ofdifferent types, e.g., macro BSs, pico BSs, femto BSs, relay BSs, and/orthe like. These different types of BSs may have different transmit powerlevels, different coverage areas, and different impacts on interferencein wireless network 100. For example, macro BSs may have a high transmitpower level (e.g., 5 to 40 watts) whereas pico BSs, femto BSs, and relayBSs may have lower transmit power levels (e.g., 0.1 to 2 watts).

A network controller 130 may couple to a set of BSs and may providecoordination and control for these BSs. Network controller 130 maycommunicate with the BSs via a backhaul. The BSs may also communicatewith one another, e.g., directly or indirectly via a wireless orwireline backhaul.

UEs 120 (e.g., 120 a, 120 b, 120 c) may be dispersed throughout wirelessnetwork 100, and each UE may be stationary or mobile. A UE may also bereferred to as an access terminal, a terminal, a mobile station, asubscriber unit, a station, and/or the like. A UE may be a cellularphone (e.g., a smart phone), a personal digital assistant (PDA), awireless modem, a wireless communication device, a handheld device, alaptop computer, a cordless phone, a wireless local loop (WLL) station,a tablet, a camera, a gaming device, a netbook, a smartbook, anultrabook, a medical device or equipment, biometric sensors/devices,wearable devices (smart watches, smart clothing, smart glasses, smartwrist bands, smart jewelry (e.g., smart ring, smart bracelet)), anentertainment device (e.g., a music or video device, or a satelliteradio), a vehicular component or sensor, smart meters/sensors,industrial manufacturing equipment, a global positioning system device,or any other suitable device that is configured to communicate via awireless or wired medium.

Some UEs may be considered machine-type communication (MTC) or evolvedor enhanced machine-type communication (eMTC) UEs. MTC and eMTC UEsinclude, for example, robots, drones, remote devices, sensors, meters,monitors, location tags, and/or the like, that may communicate with abase station, another device (e.g., remote device), or some otherentity. A wireless node may provide, for example, connectivity for or toa network (e.g., a wide area network such as Internet or a cellularnetwork) via a wired or wireless communication link. Some UEs may beconsidered Internet-of-Things (IoT) devices, and/or may be implementedas NB-IoT (narrowband internet of things) devices. Some UEs may beconsidered a Customer Premises Equipment (CPE). UE 120 may be includedinside a housing that houses components of UE 120, such as processorcomponents, memory components, and/or the like.

In general, any number of wireless networks may be deployed in a givengeographic area. Each wireless network may support a particular RAT andmay operate on one or more frequencies. A RAT may also be referred to asa radio technology, an air interface, and/or the like. A frequency mayalso be referred to as a carrier, a frequency channel, and/or the like.Each frequency may support a single RAT in a given geographic area inorder to avoid interference between wireless networks of different RATs.In some cases, NR or 5G RAT networks may be deployed.

In some aspects, two or more UEs 120 (e.g., shown as UE 120 a and UE 120e) may communicate directly using one or more sidelink channels (e.g.,without using a base station 110 as an intermediary to communicate withone another). For example, the UEs 120 may communicate usingpeer-to-peer (P2P) communications, device-to-device (D2D)communications, a vehicle-to-everything (V2X) protocol (e.g., which mayinclude a vehicle-to-vehicle (V2V) protocol, a vehicle-to-infrastructure(V2I) protocol, and/or the like), a mesh network, and/or the like. Inthis case, the UE 120 may perform scheduling operations, resourceselection operations, and/or other operations described elsewhere hereinas being performed by the base station 110.

As indicated above, FIG. 1 is provided as an example. Other examples maydiffer from what is described with regard to FIG. 1.

FIG. 2 shows a block diagram of a design 200 of base station 110 and UE120, which may be one of the base stations and one of the UEs in FIG. 1.Base station 110 may be equipped with T antennas 234 a through 234 t,and UE 120 may be equipped with R antennas 252 a through 252 r, where ingeneral T≥1 and R≥1.

At base station 110, a transmit processor 220 may receive data from adata source 212 for one or more UEs, select one or more modulation andcoding schemes (MCS) for each UE based at least in part on channelquality indicators (CQIs) received from the UE, process (e.g., encodeand modulate) the data for each UE based at least in part on the MCS(s)selected for the UE, and provide data symbols for all UEs. Transmitprocessor 220 may also process system information (e.g., for semi-staticresource partitioning information (SRPI) and/or the like) and controlinformation (e.g., CQI requests, grants, upper layer signaling, and/orthe like) and provide overhead symbols and control symbols. Transmitprocessor 220 may also generate reference symbols for reference signals(e.g., the cell-specific reference signal (CRS)) and synchronizationsignals (e.g., the primary synchronization signal (PSS) and secondarysynchronization signal (SSS)). A transmit (TX) multiple-inputmultiple-output (MIMO) processor 230 may perform spatial processing(e.g., precoding) on the data symbols, the control symbols, the overheadsymbols, and/or the reference symbols, if applicable, and may provide Toutput symbol streams to T modulators (MODs) 232 a through 232 t. Eachmodulator 232 may process a respective output symbol stream (e.g., forOFDM and/or the like) to obtain an output sample stream. Each modulator232 may further process (e.g., convert to analog, amplify, filter, andupconvert) the output sample stream to obtain a downlink signal. Tdownlink signals from modulators 232 a through 232 t may be transmittedvia T antennas 234 a through 234 t, respectively. According to variousaspects described in more detail below, the synchronization signals canbe generated with location encoding to convey additional information.

At UE 120, antennas 252 a through 252 r may receive the downlink signalsfrom base station 110 and/or other base stations and may providereceived signals to demodulators (DEMODs) 254 a through 254 r,respectively. Each demodulator 254 may condition (e.g., filter, amplify,downconvert, and digitize) a received signal to obtain input samples.Each demodulator 254 may further process the input samples (e.g., forOFDM and/or the like) to obtain received symbols. A MIMO detector 256may obtain received symbols from all R demodulators 254 a through 254 r,perform MIMO detection on the received symbols if applicable, andprovide detected symbols. A receive processor 258 may process (e.g.,demodulate and decode) the detected symbols, provide decoded data for UE120 to a data sink 260, and provide decoded control information andsystem information to a controller/processor 280. A channel processormay determine reference signal received power (RSRP), received signalstrength indicator (RSSI), reference signal received quality (RSRQ),channel quality indicator (CQI), and/or the like. In some aspects, oneor more components of UE 120 may be included in a housing.

On the uplink, at UE 120, a transmit processor 264 may receive andprocess data from a data source 262 and control information (e.g., forreports comprising RSRP, RSSI, RSRQ, CQI, and/or the like) fromcontroller/processor 280. Transmit processor 264 may also generatereference symbols for one or more reference signals. The symbols fromtransmit processor 264 may be precoded by a TX MIMO processor 266 ifapplicable, further processed by modulators 254 a through 254 r (e.g.,for DFT-s-OFDM, CP-OFDM, and/or the like), and transmitted to basestation 110. At base station 110, the uplink signals from UE 120 andother UEs may be received by antennas 234, processed by demodulators232, detected by a MIMO detector 236 if applicable, and furtherprocessed by a receive processor 238 to obtain decoded data and controlinformation sent by UE 120. Receive processor 238 may provide thedecoded data to a data sink 239 and the decoded control information tocontroller/processor 240. Base station 110 may include communicationunit 244 and communicate to network controller 130 via communicationunit 244. Network controller 130 may include communication unit 294,controller/processor 290, and memory 292.

Controller/processor 240 of base station 110, controller/processor 280of UE 120, and/or any other component(s) of FIG. 2 may perform one ormore techniques associated with sequence transmissions for sidelinkcommunications, as described in more detail elsewhere herein. Forexample, controller/processor 240 of base station 110,controller/processor 280 of UE 120, and/or any other component(s) ofFIG. 2 may perform or direct operations of, for example, process 1000 ofFIG. 10, process 1100 of FIG. 11, and/or other processes as describedherein. Memories 242 and 282 may store data and program codes for basestation 110 and UE 120, respectively. A scheduler 246 may schedule UEsfor data transmission on the downlink and/or uplink.

In some aspects, UE 120 may include means for generating a pseudorandomnoise (PN) sequence, means for modulating the PN sequence based at leastin part on a modulation order parameter, means for transmitting the PNsequence in one or more symbols prior to transmitting sidelink data, andmeans for transmitting the sidelink data in a plurality of symbols thatare subsequent in time relative to the one or more symbols used totransmit the PN sequence. In some aspects, such means may include one ormore components of UE 120 described in connection with FIG. 2.Furthermore, in some aspects, the modulated PN sequence may be used forautomatic gain control (AGC) training at a device that receives themodulated PN sequence that UE 120 transmits in the one or more symbolsthat are earlier in time relative to the symbols used to transmit thesidelink data.

Additionally, or alternatively, in some aspects UE 120 may include meansfor receiving one or more AGC symbols carrying a modulated PN sequencein one or more symbols prior to receiving sidelink data, means forconfiguring a gain for one or more receive components based on one ormore signal characteristics associated with the one or more AGC symbols,means for receiving the sidelink data in a plurality of symbols that aresubsequent in time relative to the one or more symbols in which the oneor more AGC symbols carrying the modulated PN sequence are received, andmeans for applying the configured gain to process the sidelink data. Insome aspects, such means may include one or more components of UE 120described in connection with FIG. 2.

As indicated above, FIG. 2 is provided as an example. Other examples maydiffer from what is described with regard to FIG. 2.

FIG. 3 shows an example frame structure 300 for frequency divisionduplexing (FDD), on a sidelink between UEs, in a telecommunicationssystem (e.g., LTE, 5G NR, and/or the like). The transmission timelinefor the sidelink may be partitioned into units of radio frames(sometimes referred to as frames), where t represents time. Each radioframe may have a predetermined duration (e.g., 10 milliseconds (ms)) andmay be partitioned into a set of Z (Z≥1) subframes (e.g., with indicesof 0 through Z−1). Each subframe may have a predetermined duration(e.g., 1 ms) and may include a set of slots (e.g., 2^(m) slots persubframe are shown in FIG. 3, where m is a numerology used for atransmission, such as 0, 1, 2, 3, 4, and/or the like). Each slot mayinclude a set of L symbol periods. For example, each slot may includefourteen symbol periods (e.g., as shown in FIG. 3), seven symbolperiods, or another number of symbol periods. In a case where thesubframe includes two slots (e.g., when m=1), the subframe may include2L symbol periods, where the 2L symbol periods in each subframe may beassigned indices of 0 through 2L−1. In some aspects, a scheduling unitfor the FDD may be frame-based, subframe-based, slot-based,symbol-based, and/or the like.

While some techniques are described herein in connection with frames,subframes, slots, and/or the like, these techniques may equally apply toother types of wireless communication structures, which may be referredto using terms other than “frame,” “subframe,” “slot,” and/or the likein 5G NR. In some aspects, a wireless communication structure may referto a periodic time-bounded communication unit defined by a wirelesscommunication standard and/or protocol. Additionally, or alternatively,different configurations of wireless communication structures than thoseshown in FIG. 3 may be used.

In certain telecommunications (e.g., NR), a base station may transmitsynchronization signals. For example, a base station may transmit aprimary synchronization signal (PSS), a secondary synchronization signal(SSS), and/or the like, on a downlink for each cell supported by thebase station. The PSS and SSS may be used by UEs for cell search andacquisition. For example, the PSS may be used by UEs to determine symboltiming, and the SSS may be used by UEs to determine a physical cellidentifier, associated with the base station, and frame timing. The basestation may also transmit a physical broadcast channel (PBCH). The PBCHmay carry some system information, such as system information thatsupports initial access by UEs. In some aspects, the base station maytransmit the PSS, the SSS, and/or the PBCH in accordance with asynchronization communication hierarchy (e.g., a synchronization signal(SS) hierarchy) including multiple synchronization communications (e.g.,SS blocks).

As indicated above, FIG. 3 is provided as an example. Other examples maydiffer from what is described with regard to FIG. 3.

FIG. 4 shows an example slot format 400 with a normal cyclic prefix. Theavailable time frequency resources may be partitioned into resourceblocks. Each resource block may cover a set of subcarriers (e.g., 12subcarriers) in one slot and may include a number of resource elements.Each resource element may cover one subcarrier in one symbol period(e.g., in time) and may be used to send one modulation symbol, which maybe a real or complex value. For example, as shown in FIG. 4, an earliestOFDM symbol in the slot may include one or more resource elements thatare used to send an AGC symbol from a transmitting device to a receivingdevice, as described in further detail elsewhere herein.

An interlace structure may be used for the sidelink for FDD in certaintelecommunications systems (e.g., LTE, 5G NR, and/or the like). Forexample, Q interlaces with indices of 0 through Q−1 may be defined,where Q may be equal to 4, 6, 8, 10, or some other value. Each interlacemay include slots that are spaced apart by Q frames. In particular,interlace q may include slots q, q+Q, q+2Q, and/or the like, where q E{0, . . . , Q−1}.

While aspects of the examples described herein may be associated with NRor 5G technologies, aspects of the present disclosure may be applicablewith other wireless communication systems. New Radio (NR) may refer toradios configured to operate according to a new air interface (e.g.,other than Orthogonal Frequency Divisional Multiple Access (OFDMA)-basedair interfaces) or fixed transport layer (e.g., other than InternetProtocol (IP)). In some aspects, NR may utilize OFDM with a CP (hereinreferred to as cyclic prefix OFDM or CP-OFDM) and/or SC-FDM on theuplink, may utilize CP-OFDM on the downlink and include support forhalf-duplex operation using time division duplexing (TDD). In aspects,NR may, for example, utilize OFDM with a CP (herein referred to asCP-OFDM) and/or discrete Fourier transform spread orthogonalfrequency-division multiplexing (DFT-s-OFDM) on the uplink, may utilizeCP-OFDM on the downlink and include support for half-duplex operationusing TDD. NR may include Enhanced Mobile Broadband (eMBB) servicetargeting wide bandwidth (e.g., 80 megahertz (MHz) and beyond),millimeter wave (mmW) targeting high carrier frequency (e.g., 60gigahertz (GHz)), massive MTC (mMTC) targeting non-backward compatibleMTC techniques, and/or mission critical targeting ultra-reliablelow-latency communications (URLLC) service.

In some aspects, a single component carrier bandwidth of 100 MHz may besupported. NR resource blocks may span 12 sub-carriers with asub-carrier bandwidth of 60 or 120 kilohertz (kHz) over a 0.1millisecond (ms) duration. Each radio frame may include 40 slots and mayhave a length of 10 ms. Consequently, each slot may have a length of0.25 ms. Each slot may indicate a link direction for data transmissionand the link direction for each slot may be dynamically switched. Eachsidelink slot may include a data region including one or more symbolsfor communicating sidelink data as well as a control region includingone or more symbols for communicating control data.

Beamforming may be supported and beam direction may be dynamicallyconfigured. MIMO transmissions with precoding may also be supported.MIMO configurations in the DL may support up to 8 transmit antennas withmulti-layer DL transmissions up to 8 streams and up to 2 streams per UE.Multi-layer transmissions with up to 2 streams per UE may be supported.Aggregation of multiple cells may be supported with up to 8 servingcells. Alternatively, NR may support a different air interface, otherthan an OFDM-based interface. NR networks may include entities such ascentral units or distributed units.

As indicated above, FIG. 4 is provided as an example. Other examples maydiffer from what is described with regard to FIG. 4.

In some circumstances, two or more subordinate entities (e.g., UEs) maycommunicate with each other using sidelink signals. Real-worldapplications of such sidelink communications may include public safety,proximity services, UE-to-network relaying, device-to-device (D2D)communications, vehicle-to-vehicle (V2V) communications, Internet ofEverything (IoE) communications, IoT communications, mission-criticalmesh, and/or various other suitable applications. Generally, a sidelinksignal may refer to a signal communicated from one subordinate entity(e.g., a first UE) to another subordinate entity (e.g., a second UE)without relaying that communication through a scheduling entity (e.g., aBS), even though the scheduling entity may be utilized for schedulingand/or control purposes. In some aspects, the sidelink signals may becommunicated using a licensed spectrum (unlike wireless local areanetworks, which typically use an unlicensed spectrum).

Because sidelink communications occur between subordinate entities,there can be significant variation in sidelink signal characteristics(e.g., signal power, noise, interference, and/or the like) from one slotto the next (or from one transmission to the next). For example, a UEthat transmits sidelink data in a current slot may or may not transmitagain in a subsequent slot. In another example, a UE that is nottransmitting sidelink data in a current slot may start to transmitsidelink data in a subsequent slot. Accordingly, because sidelinkcommunications occur between subordinate entities without using a basestation as an intermediary, the sidelink signal characteristics can varydepending on the UEs that are engaged in sidelink communications in agiven area at a given time. This is in contrast to wirelesscommunications that traverse a base station, which generally use powercontrol and/or other mechanisms to maintain relatively stable signalcharacteristics that do not exhibit significant fluctuations in signalpower.

Accordingly, in sidelink communications, a receiving device that may beattempting to receive a signal for a particular slot may performautomatic gain control (AGC) training, which refers to mechanisms totune or otherwise configure a radio frequency front end (RFFE) and/orother receive components to match the received signal power and therebyprevent the receive components from becoming saturated. For example, AGCis often implemented using one or more circuits (e.g., a closed-loopfeedback regulating circuit) to maintain a stable signal level at anoutput stage regardless of variations in the signal level at an inputstage. Accordingly, when the receiving device does not perform AGCtraining before attempting to receive sidelink data and/or performs AGCtraining using one or more OFDM symbols that are also used tocommunicate sidelink data, the OFDM symbol(s) used to communicate thesidelink data may not be received correctly, potentially leading to lossof the sidelink data.

Some aspects described herein provide techniques and apparatuses tocommunicate a modulated sequence (e.g., a pseudorandom noise (PN)sequence) in one or more OFDM symbols for the purpose of AGC training ata receiving UE prior to communicating sidelink data in subsequent OFDMsymbols. For example, prior to communicating sidelink data, one or moreOFDM symbols may be dedicated to communicating the modulated sequence toenable AGC training at the receiving UE, whereby the one or more OFDMsymbols used to communicate the modulated sequence may be referred toherein as AGC symbols and/or the like. Accordingly, even if the one ormore AGC symbols are lost or otherwise received incorrectly, there is noimpact to sidelink data channel processing at the receiving UE (e.g.,there may be no decoding error due to a loss of data symbols because theAGC symbols do not carry any sidelink data).

In some aspects, examples described herein may dedicate one or more OFDMsymbols that are earliest in time within a slot to communicate themodulated sequence used to enable AGC training at the receiving UE.However, these examples are for illustration purposes only, as the AGCsymbol(s) carrying the modulated sequence may be generally positioned intime prior to one or more OFDM symbols that are used to communicatesidelink data (e.g., when a channel and/or transmission does not startfrom an earliest symbol in a slot, as may be the case for a feedbackchannel).

FIG. 5 is a block diagram illustrating an example 500 of sequencetransmission for sidelink communications, in accordance with variousaspects of the present disclosure. As shown in FIG. 5, example 500 mayinclude UE 120 a and UE 120 e communicating via a sidelink in a wirelessnetwork (e.g., wireless network 100). In some aspects, the sidelink maybe configured with a frame structure, such as the frame structure 300shown in FIG. 3 and/or another sidelink frame structure, and thesidelink may be configured with a slot format, such as the slot format400 shown in FIG. 4 and/or another sidelink slot format. In example 500,UE 120 a may be acting as a transmitter to transmit sidelink data to UE120 e, which may be acting as a receiver. However, in some cases, theseroles may be dynamically switched.

As shown in FIG. 5, and by reference number 502, UE 120 a may generate amodulated PN sequence to be used for AGC training by UE 120 e. Forexample, the PN sequence may be a Gold sequence (also known as a Goldcode) generated based on a multiplication of two maximum lengthsequences (m-sequences). In some aspects, at least one of them-sequences used to generate the PN sequence may be initializedaccording to an initial sequence state, which may be based on one ormore parameters that are selected to randomize potential interferencewith one or more PN sequences that may be transmitted by other UEs usingthe same resources as UE 120 a. For example, the one or more parametersmay include an index of a frame (e.g., a frame number) to be used totransmit the PN sequence, an index of a slot (e.g., a slot number) to beused to transmit the PN sequence, an index of an OFDM symbol (e.g., anOFDM symbol number) to be used to transmit the PN sequence, a configuredidentification, an index associated with a sub-channel to be used totransmit the PN sequence, an identification of UE 120 a, a parameterincluding one or more integer values configured by a base station ornetwork node, a random number, and/or the like.

Accordingly, when the index of the frame is used to initialize the PNsequence, the PN sequence may differ from one frame to another.Similarly, when the index of the slot is used to initialize the PNsequence, the PN sequence may differ from slot to slot, and the PNsequence may further differ from one OFDM symbol to another when theindex of the OFDM symbol is used to initialize the PN sequence. In someaspects, the configured identification may be a particular identifierthat UE 120 a uses for the purpose of initializing the PN sequence. Insome aspects, the index associated with the sub-channel to be used totransmit the PN sequence may be used for sidelink communications inwhich available data transmission bandwidth is partitioned into multiplesub-channels, in which case the PN sequence may be transmitted onmultiple sub-channels and the index may be an index of a first one ofthe multiple sub-channels.

In some aspects, as mentioned above, initializing the PN sequence basedon one or more of the parameters described above may randomizeinterference with other UEs that may be transmitting on the sameresource(s). In particular, the parameters (or combination ofparameters) that are used may be selected to ensure that the PNsequences transmitted by UE 120 a are different from the PN sequence(s)that one or more other UEs are transmitting on the same resource(s), byvarying a seed used to initialize the PN sequence. For example, if theinitialization utilizes only the index of the frame, different UEs maygenerate the same PN sequence because the frame number is the same forall UEs. These PN sequences may be combined over-the-air, which mayresult in UE 120 e that is intended to receive the PN sequence generatedby UE 120 a failing to correctly perform AGC training based on the PNsequence due to an overlap in AGC symbols. However, a data channel usedby the different UEs may vary, whereby using other parameters that maybe specific to a particular UE may randomize the respective PNsequences, which increases a likelihood that the UE 120 e intended toreceive the PN sequence will be able to correctly perform AGC trainingbased on the PN sequence.

In some aspects, as mentioned above, the PN sequence may be a Goldsequence (or Gold code) that is generated based on two m-sequences,including at least one m-sequence initialized according to an initialsequence state, which may be denoted as c_(init). For example, UE 120 amay determine the initial sequence state based on the functionc_(init)=ƒ(N_(symb) ^(slot), n_(s,ƒ) ^(μ)), where N_(symb) ^(slot) is aquantity of OFDM symbols in a slot, and n_(s,ƒ) ^(μ) is a slot number(index) within a frame; the function c_(init)=ƒ(N_(symb) ^(slot),n_(s,ƒ) ^(μ), l), where l is an OFDM symbol number (index) within theslot; the function c_(init)=ƒ(N_(symb) ^(slot), n_(s,ƒ) ^(μ), n_(ID)),where n_(ID) is an identifier associated with UE 120 a (e.g., a Layer 1identifier assigned to UE 120 a for V2X or other sidelinkcommunications), and/or the like. In one specific example, UE 120 a maydetermine the initial sequence state based on the functionc_(init)=2⁸(N_(symb) ^(slot)n_(s,ƒ) ^(μ)+1)(2n_(ID)+1)+n_(ID).

In some aspects, in addition to configuring the initial sequence statebased on one or more parameters as described above, UE 120 a maydetermine various parameters for generating the modulated PN sequence.For example, the parameters for generating the modulated PN sequence mayinclude a modulation order parameter (Q_(m)) for modulating the PNsequence, a quantity of earliest symbols in a slot to be dedicated tocommunicating the modulated PN sequence (L_(AGC)), a sidelink datachannel transmission bandwidth (N_(SC)), a number of layers for thesidelink data transmission (v) (e.g., a number of antenna ports to beused to communicate the modulated PN sequence), and/or the like.

In some aspects, the modulation order parameter Q_(m) for modulating thePN sequence may be predefined to be a particular modulation orderindependent of a modulation to be used for subsequent sidelink datatransmissions. For example, the modulation order may be predefined to beQuadrature Phase Shift Keying (QPSK) modulation. In this case, aquantity of ports to be used to transmit the modulated PN sequence maybe predefined (e.g., transmission of the modulated PN sequence may befixed to be a one-port or one-layer transmission, a two-port ortwo-layer transmission, and/or the like). Additionally, oralternatively, a quantity of ports to be used to transmit the modulatedPN sequence may be equivalent to a quantity of ports to be used forsidelink data transmissions (e.g., after the modulated PN sequence istransmitted).

Additionally, or alternatively, the modulation order parameter Q_(m) formodulating the PN sequence may be based on a modulation scheme to beused for the sidelink data transmissions to be performed subsequent totransmitting the modulated PN sequence. For example, when the modulationscheme to be used for the sidelink data transmissions is 16 quadratureamplitude modulation (QAM), the modulation order for the PN sequence mayalso be 16QAM, which results in Q_(m) having a value of 4. In otherexamples, the modulation order for the sidelink data transmissions andthe PN sequence may be 64QAM (in which case Q_(m)=6), 256QAM (in whichcase Q_(m)=8), QPSK (in which case Q_(m)=2), and/or the like. In thiscase, by using the same modulation order for the PN sequence and thesubsequent data transmissions, resources are conserved at UE 120 a andUE 120 e because the PN sequence that is transmitted in the first one orfew symbols of a slot for AGC training may have the same physical layerprocessing as the subsequent symbols used to transmit sidelink data.

Furthermore, in some aspects, UE 120 a may determine one or moreadditional parameters for modulating the PN sequence that are based onphysical layer processing used for subsequent sidelink datatransmissions. For example, a quantity of antenna ports that UE 120 auses to transmit the modulated PN sequence may be equivalent to aquantity of antenna ports to be used by UE 120 a for the sidelink datatransmissions (e.g., when the sidelink data is a two-port transmission,meaning that there are two ports of demodulation reference signals(DMRS) for the sidelink data, the PN sequence may also be transmittedusing the same two ports). Furthermore, when UE 120 a applies precodingto the sidelink data transmissions, UE 120 a may apply the sameprecoding to the modulated PN sequence used for AGC training at UE 120e.

In some aspects, UE 120 a may further determine the quantity of earliestsymbols in a slot to be dedicated to communicating the modulated PNsequence, denoted herein as L_(AGC). For example, UE 120 a may generatea PN sequence based on the initial sequence state as described above,modulate the PN sequence according to the modulation order parameterQ_(m), and determine a mapping between the modulated PN sequence and theearliest L_(AGC) available OFDM symbols in a slot to be used forsidelink data transmissions, where L_(AGC) is an integer having a valuegreater than or equal to one. For example, L_(AGC) may have a predefinedvalue (e.g., fixed to be one, two, and/or the like). Additionally, oralternatively, L_(AGC) may have a value that depends on a sub-carrierspacing (e.g., L_(AGC) may be one when the sub-carrier spacing is 15 kHzor 30 kHz, two when the sub-carrier spacing is 60 kHz, and/or the like).

In some aspects, UE 120 a may further determine a length for the PNsequence to be modulated based on various parameters that relate to thesidelink data channel between UE 120 a and UE 120 e, the value forL_(AGC), a quantity of OFDM symbols to be mapped to the PN sequence,and/or the like. For example, in cases where the PN sequence istransmitted in one OFDM symbol that is earliest in a slot and/or thesame PN sequence is repeated in multiple OFDM symbols at the start of aslot, UE 120 a may determine the length of the PN sequence based on thetransmission bandwidth of the data, N_(sc), expressed as a quantity ofsub-carriers or resource elements (REs), the modulation order Q_(m), anda quantity of antenna ports (or layers) transmitting the data (v). Inthis case, the PN sequence may have a length (len) determined using thefunction len=v×Q_(m)×N_(sc)/C, where C is an integer and C≥1.

For example, when C=1, UE 120 a may generate the PN sequence with alength len=v×Q_(m)×N_(sc), and UE 120 a may then modulate the PNsequence to v×N, modulation symbols, which may be sequentially mapped toeach sub-carrier of a particular OFDM symbol used for AGC training foreach of v ports. In another example, when C>1, the PN sequence may havea shorter length given by len=v×Q_(m)×N_(sc)/C, in which case UE 120 amay modulate the PN sequence to v×N_(sc)/C modulation symbols, which maybe mapped to each C^(th) sub-carrier of a particular OFDM symbol usedfor AGC training for each of v ports. Furthermore, when L_(AGC)>1, themodulation symbols may be repeated across the L_(AGC) OFDM symbols.

Accordingly, in one example, the modulation order parameter may bepredefined to be QPSK, in which case Q_(m) has a value of 2, and aquantity of ports to be used to transmit the PN sequence may be fixed atone port. In this example, v equals one, so the PN sequence has a lengthgiven by len=2×N_(sc)/C. In this case, when C equals one, the length ofthe PN sequence is 2×N_(sc), which is then modulated to N_(sc) QPSKsymbols and sequentially mapped to each sub-carrier. Additionally, oralternatively, when C is greater than one, the length of the PN sequenceis 2×N_(sc)/C, which is modulated to N_(sc)/C QPSK symbols and mapped toevery C^(th) sub-carrier (e.g., every other sub-carrier when C=2, everythird sub-carrier when C=3, and/or the like).

As further shown in FIG. 5, and by reference number 504, UE 120 a maytransmit the modulated PN sequence to UE 120 e on a sidelink in one ormore earliest symbols of a slot to be used to transmit sidelink data.For example, in some aspects, UE 120 a may transmit the modulated PNsequence in an earliest (i.e., first) L_(AGC) OFDM symbol(s) of a slotwhen UE 120 a is transmitting sidelink data in the slot, in which caseeach slot that includes sidelink data includes one or more earliestsymbols that are dedicated to communicating a modulated PN sequence tobe used for AGC training at UE 120 e. In another example, when UE 120 aemploys slot aggregation or hybrid automatic repeat request (HARQ)retransmission (repetition) to transmit sidelink data across multipleconsecutive slots, UE 120 a may transmit the modulated PN sequence inthe earliest available OFDM symbol(s) of only the first of the multipleconsecutive slots. In some aspects, transmission of the PN sequence usedfor AGC training may be configured by a network node (e.g., a basestation may send signaling to UE 120 a and/or UE 120 e to instruct UEs120 a, 120 e to enable and/or disable the PN sequence transmission).

As further shown in FIG. 5, and by reference number 506, one or more AGCsymbols carrying the PN sequence may be received by UE 120 e, which mayconfigure a gain for one or more receive components based on one or moresignal characteristics associated with the AGC symbol(s). For example,UE 120 e may be configured to use the earliest OFDM symbols in the slotfor AGC training, and may therefore measure a received signal strengthor received signal power for the earliest OFDM symbols that are carryingthe PN sequence. Accordingly, UE 120 e may use the measurements ofreceived signal strength or received signal power for the earliest OFDMsymbols in the slot and set the gain for the one or more receivecomponents based on the measurements. Notably, UE 120 e receiving the PNsequence may only measure the received signal power of the received PNsequence without demodulating the PN sequence. In this way, UE 120 e mayuse the received PN sequence for AGC training purposes, whereby the gainthat is configured based on the signal characteristics of the PNsequence may be applied to process subsequent symbols carrying sidelinkdata. Accordingly, as further shown in FIG. 5, and by reference number508, UE 120 a may transmit, on the sidelink, sidelink data in a set ofsymbols of the slot that are subsequent in time relative to the earliestsymbol(s) used to transmit the PN sequence. For example, in someaspects, the sidelink data may include one or more information bitscarried in a control channel (e.g., a physical sidelink controlchannel), one or more information bits carried in a shared channel(e.g., a physical sidelink shared channel), one or more information bitscarried in a broadcast channel (e.g., a physical sidelink broadcastchannel), one or more information bits carried in a feedback channel(e.g., a physical sidelink feedback channel), and/or the like. Asfurther shown in FIG. 5, and by reference number 510, UE 120 e may applythe gain that was configured based on the signal characteristics of thePN sequence to process the sidelink data.

As indicated above, FIG. 5 is provided as an example. Other examples maydiffer from what is described with respect to FIG. 5.

FIG. 6 is a block diagram illustrating an example slot structure 600 fora single-slot transmission of a sequence for sidelink communications, inaccordance with various aspects of the present disclosure. For example,in FIG. 6, a transmission slot includes fourteen OFDM symbols, and atransmitting UE has an available transmission bandwidth that includes aportion of frequency spectrum. In the example illustrated in FIG. 6,L_(AGC) may have a value of one, whereby a first OFDM symbol in the slot(i.e., an earliest OFDM symbol in time) is dedicated to carrying a PNsequence to be used for AGC training at a receiving UE. Accordingly, thetransmitting UE may generate a modulated PN sequence as described infurther detail elsewhere herein and transmit the modulated PN sequenceas an AGC symbol in the earliest symbol of the slot.

The AGC symbol may be received by the receiving UE, which may configurea gain for one or more receive components based on one or more signalcharacteristics (e.g., a received signal power) associated with the AGCsymbol. Accordingly, when the transmitting UE transmits sidelink data inthe remaining slots that are subsequent in time relative to the earliestslot used to communicate the modulated PN sequence, the receiving UE mayapply the configured gain to process the sidelink data. Furthermore, ifthe receiving UE does not correctly receive the AGC symbol, there is nodata loss because the AGC symbol does not carry any sidelink data.

As indicated above, FIG. 6 is provided as an example. Other examples maydiffer from what is described with respect to FIG. 6.

FIG. 7 is a block diagram illustrating an example slot structure formulti-slot transmissions for sidelink communications, in accordance withvarious aspects of the present disclosure. For example, as shown in FIG.7, and by reference number 700, the multi-slot transmissions may beconfigured to dedicate the earliest L_(AGC) symbols in each slot to AGCtraining, whereby a modulated PN sequence used for AGC training at areceiving UE may be communicated in the earliest L_(AGC) symbols in eachslot. Additionally, or alternatively, as shown by reference number 710,the multi-slot transmissions may be configured to dedicate the earliestL_(AGC) symbols in only a first slot to AGC training, whereby amodulated PN sequence used for AGC training at a receiving UE may becommunicated in the earliest L_(AGC) symbols in the first slot and allremaining slots may be used to communicate sidelink data. In this case,because the multi-slot transmissions include two or more consecutivetransmissions by a transmitting UE, there may be no apparent orsignificant fluctuations in received signal power and/or the like at thereceiving UE across slots, whereby communicating the AGC symbol insubsequent slots may be unnecessary.

As indicated above, FIG. 7 is provided as an example. Other examples maydiffer from what is described with respect to FIG. 7.

FIG. 8 is a block diagram illustrating an example slot structure fortransmitting a sequence for sidelink communications in multiple symbols,in accordance with various aspects of the present disclosure. Inparticular, the sequence may be transmitted in multiple symbols whenL_(AGC) is greater than one, when multiple antenna ports (or layers) areused to transmit the sequence, and/or the like. In some aspects, whenthe sequence is transmitted in multiple symbols, there are variouspossible slot configurations for communicating the sequence.

For example, as shown in FIG. 8, and by reference number 800, aplurality of earliest symbols in a slot (e.g., two in the illustratedexample) may be used to communicate the PN sequence. In this case, theplurality of earliest symbols in the slot may correspond to AGC symbols,and different PN sequences may be generated for each of the plurality ofsymbols. For example, a first PN sequence may be transmitted in thefirst symbol of the slot, and a second PN sequence may be transmitted inthe second symbol of the slot. Additionally, or alternatively, as shownby reference number 810, a single PN sequence may be generated andrepeated for each of the plurality of AGC symbols that are earliest intime within the slot. For example, a transmitting UE may generate andmodulate a PN sequence, which may be transmitted in the first symbol ofthe slot and transmitted again in the second symbol of the slot.

Additionally, or alternatively, as shown by reference number 820, a longPN sequence may be generated and transmitted across the plurality of AGCsymbols that are earliest in time within the slot. For example, atransmitting UE may generate and modulate a PN sequence having aparticular length that is based on a modulation order parameter (Q_(m))for modulating the PN sequence, the quantity of earliest symbols in aslot to be dedicated to communicating the modulated PN sequence(L_(AGC)), a sidelink data channel transmission bandwidth (N_(SC)), anumber of layers for the sidelink data transmission (v) (e.g., a numberof antenna ports to be used to communicate the modulated PN sequence),and/or the like. In some cases, the PN sequence may have a length thatexceeds a capacity of a single slot, in which case the transmitting UEmay start to transmit a first set of bits associated with the modulatedPN sequence in the first symbol of the slot and transmit a remaining setof bits in the second symbol of the slot.

As further shown in FIG. 8, and by reference number 830, a multi-layeror multi-port transmission may be used for the PN sequence. In thiscase, the transmitting UE may use the earliest L_(AGC) symbols in a slotto transmit the PN sequence via multiple antenna ports, where the AGCsymbol has the same layer and is transmitted on the same antenna portsas the sidelink data. In one example, when the PN sequence is amulti-port transmission, the PN sequence transmitted on different portsmay be different. For example, when sidelink data is communicated via atwo-layer transmission (e.g., using spatial multiplexing of two layers),the generated PN sequence may be different on the two ports. In someaspects, varying the generated PN sequence for the different ports canbe achieved using a port-specific parameter (e.g., a port number or portindex) to initialize the PN sequence to be transmitted on eachrespective port. In another example, when the PN sequence is amulti-port transmission, the PN sequence transmitted on different portsmay be the same. For example, when a data transmission mode isSpace-Frequency Block Code (SFBC), data transmitted on multiple (e.g.,two) ports may be generated from the same data using SFBC precodingtechniques. In this case, the PN sequence may be generated with anassumption that the PN sequence will be a one-layer transmission (i.e.,v=1) and then precoded using the same technique as data.

As indicated above, FIG. 8 is provided as an example. Other examples maydiffer from what is described with respect to FIG. 8.

FIG. 9 is a block diagram illustrating an example resource elementmapping for transmitting a sequence for sidelink communications, inaccordance with various aspects of the present disclosure. As shown inFIG. 9, a data channel bandwidth may be partitioned into resourceblocks, each of which include a set of resource elements (REs). Ingeneral, as mentioned above, a PN sequence may have a length that isbased on a parameter C, which is an integer having a value greater thanor equal to one based on a mapping between AGC symbol and sub-carriers.In particular, as mentioned elsewhere herein, AGC symbols may be mappedto every C^(th) sub-carrier. Accordingly, as shown in FIG. 9, and byreference number 900, each RE may be sequentially mapped to an AGCsymbol (i.e., an OFDM symbol used to communicate a PN sequence used forAGC training) in cases where C=1. As further shown in FIG. 9, and byreference number 910, every other RE may be mapped to an AGC symbol incases where C=2. In this case, assuming that the data channel bandwidthis the same for both mappings, the length of the PN sequence in caseswhere each RE is sequentially mapped to an AGC symbol may be double thelength of the PN sequence in cases where every other RE is mapped to anAGC symbol.

As indicated above, FIG. 9 is provided as an example. Other examples maydiffer from what is described with respect to FIG. 9.

FIG. 10 is a diagram illustrating an example process 1000 performed, forexample, by a UE, in accordance with various aspects of the presentdisclosure. Example process 1000 is an example where a UE (e.g., UE 120a and/or the like) performs operations associated with sequencetransmission for sidelink communications.

As shown in FIG. 10, in some aspects, process 1000 may includegenerating a PN sequence (block 1010). For example, the UE (e.g., usingtransmit processor 264, controller/processor 280, memory 282, and/or thelike) may generate a PN sequence, as described above.

As shown in FIG. 10, in some aspects, process 1000 may includemodulating the PN sequence based at least in part on a modulation orderparameter (block 1020). For example, the UE (e.g., using modulator(s)254, transmit processor 264, controller/processor 280, memory 282,and/or the like) may modulate the PN sequence based at least in part ona modulation order parameter, as described above.

As further shown in FIG. 10, in some aspects, process 1000 may includetransmitting the PN sequence in one or more symbols prior totransmitting sidelink data (block 1030). For example, the UE (e.g.,using antenna 252, transmit processor 264, controller/processor 280,memory 282, and/or the like) may transmit the PN sequence in one or moresymbols prior to transmitting sidelink data, as described above.

As further shown in FIG. 10, in some aspects, process 1000 may includetransmitting the sidelink data in a plurality of symbols that aresubsequent in time relative to the one or more symbols used to transmitthe PN sequence (block 1040). For example, the UE (e.g., using antenna252, transmit processor 264, controller/processor 280, memory 282,and/or the like) may transmit the sidelink data in a plurality ofsymbols that are subsequent in time relative to the one or more symbolsused to transmit the PN sequence, as described above.

Process 1000 may include additional aspects, such as any single aspector any combination of aspects described below and/or in connection withone or more other processes described elsewhere herein.

In a first aspect, the one or more symbols are dedicated to transmittingthe PN sequence to enable AGC training at a receiver device prior toreception of the sidelink data at the receiver device.

In a second aspect, alone or in combination with the first aspect, aquantity of the one or more symbols that are used to transmit the PNsequence is based at least in part on a subcarrier spacing.

In a third aspect, alone or in combination with one or more of the firstand second aspects, the PN sequence is based at least in part on atleast one maximum length sequence that is initialized according to aninitial sequence state that is based at least in part on a set of one ormore parameters.

In a fourth aspect, alone or in combination with one or more of thefirst through third aspects, the set of one or more parameters includeone or more of an index associated with a frame that includes a slot inwhich the PN sequence is transmitted, an index associated with the slotin which the PN sequence is transmitted, an index associated with theone or more symbols in which the PN sequence is transmitted, an indexassociated with an antenna port used to transmit the PN sequence, aconfigured identification, an index associated with a sub-channel usedto transmit the PN sequence, an identification of the UE, a parameterincluding one or more integer values, or a random number.

In a fifth aspect, alone or in combination with one or more of the firstthrough fourth aspects, the modulation order parameter has a value basedat least in part on a predefined quadrature modulation scheme.

In a sixth aspect, alone or in combination with one or more of the firstthrough fifth aspects, the modulation order parameter has a value basedat least in part on a quadrature modulation scheme used to transmit thesidelink data.

In a seventh aspect, alone or in combination with one or more of thefirst through sixth aspects, the PN sequence is transmitted on a fixedquantity of antenna ports.

In an eighth aspect, alone or in combination with one or more of thefirst through seventh aspects, the PN sequence and the sidelink data aretransmitted using an equal quantity of antenna ports.

In a ninth aspect, alone or in combination with one or more of the firstthrough eighth aspects, the PN sequence and the sidelink data aretransmitted using a same set of antenna ports.

In a tenth aspect, alone or in combination with one or more of the firstthrough ninth aspects, the PN sequence is transmitted using precoding tobe applied to the sidelink data.

In an eleventh aspect, alone or in combination with one or more of thefirst through tenth aspects, the PN sequence has a length based at leastin part on the modulation order parameter, a quantity of antenna portsused to transmit the sidelink data, and an available transmissionbandwidth for the sidelink data.

In a twelfth aspect, alone or in combination with one or more of thefirst through eleventh aspects, the PN sequence has a length based atleast in part on the modulation order parameter, a quantity of antennaports used to transmit the sidelink data, an available transmissionbandwidth for the sidelink data, and a positive integer based at leastin part on a mapping between symbols of the modulated PN sequence and aset of subcarriers.

In a thirteenth aspect, alone or in combination with one or more of thefirst through twelfth aspects, the PN sequence has a length based atleast in part on the modulation order parameter, a quantity of antennaports used to transmit the sidelink data, an available transmissionbandwidth for the sidelink data, a first positive integer based at leastin part on a mapping between symbols of the modulated PN sequence and aset of subcarriers, and a second positive integer that is based at leastin part on a quantity of the one or more symbols that are used totransmit the PN sequence.

In a fourteenth aspect, alone or in combination with one or more of thefirst through thirteenth aspects, a transmission of the PN sequence isrepeated in one or more symbols of one or more subsequent slots in whichthe UE transmits the sidelink data.

In a fifteenth aspect, alone or in combination with one or more of thefirst through fourteenth aspects, when the UE transmits the sidelinkdata in multiple consecutive slots, the PN sequence is transmitted inonly a first one of the multiple consecutive slots.

In a sixteenth aspect, alone or in combination with one or more of thefirst through fifteenth aspects, the UE receives, from a network node, asignaling message related to subsequent transmissions of the PN sequenceand disables the subsequent transmissions of the PN sequence based atleast in part on the signaling message.

In a seventeenth aspect, alone or in combination with one or more of thefirst through sixteenth aspects, the sidelink data includes one or moreinformation bits carried in one or more of a control channel, a sharedchannel, a broadcast channel, or a feedback channel.

Although FIG. 10 shows example blocks of process 1000, in some aspects,process 1000 may include additional blocks, fewer blocks, differentblocks, or differently arranged blocks than those depicted in FIG. 10.Additionally, or alternatively, two or more of the blocks of process1000 may be performed in parallel.

FIG. 11 is a diagram illustrating an example process 1100 performed, forexample, by a UE, in accordance with various aspects of the presentdisclosure. Example process 1100 is an example where a user equipment(e.g., UE 120 e and/or the like) performs operations associated withsequence transmission for sidelink communications.

As shown in FIG. 11, in some aspects, process 1100 may include receivingone or more AGC symbols carrying a modulated PN sequence in one or moresymbols prior to receiving sidelink data (block 1110). For example, theUE (e.g., using antenna 252, receive processor 258, controller/processor280, memory 282, and/or the like) may receive one or more AGC trainingsymbols carrying a modulated PN sequence in one or more symbols prior toreceiving sidelink data, as described above.

As further shown in FIG. 11, in some aspects, process 1100 may includeconfiguring a gain for one or more receive components based on one ormore signal characteristics associated with the one or more AGC symbols(block 1120). For example, the UE (e.g., using receive processor 258,controller/processor 280, memory 282, and/or the like) may configure again for one or more receive components based on one or more signalcharacteristics associated with the one or more AGC symbols, asdescribed above.

As further shown in FIG. 11, in some aspects, process 1100 may includereceiving the sidelink data in a plurality of symbols that aresubsequent in time relative to the one or more symbols in which the oneor more AGC symbols carrying the modulated PN sequence are received(block 1130). For example, the UE (e.g., using antenna 252, receiveprocessor 258, controller/processor 280, memory 282, and/or the like)may receive the sidelink data in a plurality of symbols that aresubsequent in time relative to the one or more symbols in which the oneor more AGC symbols carrying the modulated PN sequence are received, asdescribed above.

As further shown in FIG. 11, in some aspects, process 1100 may includeapplying the configured gain to process the sidelink data (block 1140).For example, the UE (e.g., using receive processor 258,controller/processor 280, memory 282, and/or the like) may apply theconfigured gain to process the sidelink data, as described above.

Process 1100 may include additional aspects, such as any single aspector any combination of aspects described below and/or in connection withone or more other processes described elsewhere herein.

In a first aspect, the one or more signal characteristics include areceived signal power associated with the one or more AGC symbols.

In a second aspect, alone or in combination with the first aspect, theone or more AGC symbols are dedicated to carrying the modulated PNsequence to enable AGC training at the UE prior to the UE receiving thesidelink data.

In a third aspect, alone or in combination with one or more of the firstand second aspects, a quantity of the one or more AGC symbols carryingthe modulated PN sequence is based at least in part on a subcarrierspacing.

In a fourth aspect, alone or in combination with one or more of thefirst through third aspects, a transmission of the one or more AGCsymbols is repeated across multiple slots in which the UE receives thesidelink data.

In a fifth aspect, alone or in combination with one or more of the firstthrough fourth aspects, when the UE receives the sidelink data inmultiple consecutive slots, the one or more AGC symbols are received inonly a first one of the multiple consecutive slots.

Although FIG. 11 shows example blocks of process 1100, in some aspects,process 1100 may include additional blocks, fewer blocks, differentblocks, or differently arranged blocks than those depicted in FIG. 11.Additionally, or alternatively, two or more of the blocks of process1100 may be performed in parallel.

The foregoing disclosure provides illustration and description, but isnot intended to be exhaustive or to limit the aspects to the preciseform disclosed. Modifications and variations may be made in light of theabove disclosure or may be acquired from practice of the aspects.

As used herein, the term “component” is intended to be broadly construedas hardware, firmware, and/or a combination of hardware and software. Asused herein, a processor is implemented in hardware, firmware, and/or acombination of hardware and software.

As used herein, satisfying a threshold may, depending on the context,refer to a value being greater than the threshold, greater than or equalto the threshold, less than the threshold, less than or equal to thethreshold, equal to the threshold, not equal to the threshold, and/orthe like.

It will be apparent that systems and/or methods described herein may beimplemented in different forms of hardware, firmware, and/or acombination of hardware and software. The actual specialized controlhardware or software code used to implement these systems and/or methodsis not limiting of the aspects. Thus, the operation and behavior of thesystems and/or methods were described herein without reference tospecific software code—it being understood that software and hardwarecan be designed to implement the systems and/or methods based, at leastin part, on the description herein.

Even though particular combinations of features are recited in theclaims and/or disclosed in the specification, these combinations are notintended to limit the disclosure of various aspects. In fact, many ofthese features may be combined in ways not specifically recited in theclaims and/or disclosed in the specification. Although each dependentclaim listed below may directly depend on only one claim, the disclosureof various aspects includes each dependent claim in combination withevery other claim in the claim set. A phrase referring to “at least oneof” a list of items refers to any combination of those items, includingsingle members. As an example, “at least one of: a, b, or c” is intendedto cover a, b, c, a-b, a-c, b-c, and a-b-c, as well as any combinationwith multiples of the same element (e.g., a-a, a-a-a, a-a-b, a-a-c,a-b-b, a-c-c, b-b, b-b-b, b-b-c, c-c, and c-c-c or any other ordering ofa, b, and c).

No element, act, or instruction used herein should be construed ascritical or essential unless explicitly described as such. Also, as usedherein, the articles “a” and “an” are intended to include one or moreitems, and may be used interchangeably with “one or more.” Furthermore,as used herein, the terms “set” and “group” are intended to include oneor more items (e.g., related items, unrelated items, a combination ofrelated and unrelated items, and/or the like), and may be usedinterchangeably with “one or more.” Where only one item is intended, thephrase “only one” or similar language is used. Also, as used herein, theterms “has,” “have,” “having,” and/or the like are intended to beopen-ended terms. Further, the phrase “based on” is intended to mean“based, at least in part, on” unless explicitly stated otherwise.

What is claimed is:
 1. A method of wireless communication performed by auser equipment (UE), comprising: receiving one or more automatic gaincontrol (AGC) symbols carrying a modulated pseudorandom noise (PN)sequence in one or more symbols prior to receiving sidelink data;configuring a gain for one or more receive components based at least inpart on one or more signal characteristics associated with the one ormore AGC symbols; receiving the sidelink data in a plurality of symbolsthat are subsequent in time relative to the one or more symbols in whichthe one or more AGC symbols carrying the modulated PN sequence arereceived; and applying the configured gain to process the sidelink data.2. The method of claim 1, wherein the one or more signal characteristicsinclude a received signal power associated with the one or more AGCsymbols.
 3. The method of claim 1, wherein the one or more AGC symbolsare dedicated to carrying the modulated PN sequence to enable AGCtraining at the UE prior to the UE receiving the sidelink data.
 4. Themethod of claim 1, wherein a quantity of the one or more AGC symbolscarrying the modulated PN sequence is based at least in part on asubcarrier spacing.
 5. The method of claim 1, wherein a transmission ofthe one or more AGC symbols is repeated across multiple slots in whichthe UE receives the sidelink data.
 6. The method of claim 1, wherein,when the UE receives the sidelink data in consecutive slots, the one ormore AGC symbols are received in only a first one of the consecutiveslots.
 7. The method of claim 1, further comprising: measuring, based atleast in part on receiving the AGC symbols, a received signal strengthor a received signal power for one or more first received symbols of theone or more symbols carrying the modulated PN sequence, wherein the oneor more signal characteristics include the received signal strength orthe received signal power for the one or more first received symbols ofthe one or more symbols carrying the modulated PN sequence.
 8. Themethod of claim 7, wherein the received signal power is measured withoutdemodulating the modulated PN sequence.
 9. A user equipment (UE) forwireless communication, comprising: a memory; and one or more processorscoupled to the memory, the one or more processors configured to: receiveone or more automatic gain control (AGC) symbols carrying a modulatedpseudorandom noise (PN) sequence in one or more symbols prior toreceiving sidelink data; configure a gain for one or more receivecomponents based at least in part on one or more signal characteristicsassociated with the one or more AGC symbols; receive the sidelink datain a plurality of symbols that are subsequent in time relative to theone or more symbols in which the one or more AGC symbols carrying themodulated PN sequence are received; and apply the configured gain toprocess the sidelink data.
 10. The UE of claim 9, wherein the one ormore signal characteristics include a received signal power associatedwith the one or more AGC symbols.
 11. The UE of claim 9, wherein the oneor more AGC symbols are dedicated to carrying the modulated PN sequenceto enable AGC training at the UE prior to the UE receiving the sidelinkdata.
 12. The UE of claim 9, wherein a quantity of the one or more AGCsymbols carrying the modulated PN sequence is based at least in part ona subcarrier spacing.
 13. The UE of claim 9, wherein a transmission ofthe one or more AGC symbols is repeated across multiple slots in whichthe UE receives the sidelink data.
 14. The UE of claim 9, wherein, whenthe sidelink data is received in consecutive slots, the one or more AGCsymbols are received in only a first one of the consecutive slots. 15.The UE of claim 9, wherein the one or more processors are furtherconfigured to: measure, based at least in part on receiving the AGCsymbols, a received signal strength or a received signal power for oneor more first received symbols of the one or more symbols carrying themodulated PN sequence, wherein the one or more signal characteristicsinclude the received signal strength or the received signal power forthe one or more first received symbols of the one or more symbolscarrying the modulated PN sequence.
 16. The UE of claim 15, wherein thereceived signal power is measured without demodulating the modulated PNsequence.
 17. A non-transitory computer-readable medium storing a set ofinstructions for wireless communication, the set of instructionscomprising: one or more instructions that, when executed by one or moreprocessors of a user equipment (UE), cause the UE to: receive one ormore automatic gain control (AGC) symbols carrying a modulatedpseudorandom noise (PN) sequence in one or more symbols prior toreceiving sidelink data; configure a gain for one or more receivecomponents based at least in part on one or more signal characteristicsassociated with the one or more AGC symbols; receive the sidelink datain a plurality of symbols that are subsequent in time relative to theone or more symbols in which the one or more AGC symbols carrying themodulated PN sequence are received; and apply the configured gain toprocess the sidelink data.
 18. The non-transitory computer-readablemedium of claim 17, wherein the one or more signal characteristicsinclude a received signal power associated with the one or more AGCsymbols.
 19. The non-transitory computer-readable medium of claim 17,wherein the one or more AGC symbols are dedicated to carrying themodulated PN sequence to enable AGC training at the UE prior to the UEreceiving the sidelink data.
 20. The non-transitory computer-readablemedium of claim 17, wherein a quantity of the one or more AGC symbolscarrying the modulated PN sequence is based at least in part on asubcarrier spacing.
 21. The non-transitory computer-readable medium ofclaim 17, wherein a transmission of the one or more AGC symbols isrepeated across multiple slots in which the UE receives the sidelinkdata.
 22. The non-transitory computer-readable medium of claim 17,wherein, when the UE receives the sidelink data in consecutive slots,the one or more AGC symbols are received in only a first one of theconsecutive slots.
 23. The non-transitory computer-readable medium ofclaim 17, wherein the one or more instructions further cause the UE to:measure, based at least in part on receiving the AGC symbols, a receivedsignal strength or a received signal power for one or more earliestsymbols of the one or more symbols carrying the modulated PN sequence,wherein the one or more signal characteristics include the receivedsignal strength or the received signal power for the one or moreearliest symbols of the one or more symbols carrying the modulated PNsequence.
 24. The non-transitory computer-readable medium of claim 23,wherein the received signal power is measured without demodulating themodulated PN sequence.
 25. An apparatus for wireless communication,comprising: means for receiving one or more automatic gain control (AGC)symbols carrying a modulated pseudorandom noise (PN) sequence in one ormore symbols prior to receiving sidelink data; means for configuring again for one or more receive components based at least in part on one ormore signal characteristics associated with the one or more AGC symbols;means for receiving the sidelink data in a plurality of symbols that aresubsequent in time relative to the one or more symbols in which the oneor more AGC symbols carrying the modulated PN sequence are received; andmeans for applying the configured gain to process the sidelink data. 26.The apparatus of claim 25, wherein the one or more signalcharacteristics include a received signal power associated with the oneor more AGC symbols.
 27. The apparatus of claim 25, wherein the one ormore AGC symbols are dedicated to carrying the modulated PN sequence toenable AGC training at the apparatus prior to the apparatus receivingthe sidelink data.
 28. The apparatus of claim 25, wherein a quantity ofthe one or more AGC symbols carrying the modulated PN sequence is basedat least in part on a subcarrier spacing.
 29. The apparatus of claim 25,wherein a transmission of the one or more AGC symbols is repeated acrossmultiple slots in which the apparatus receives the sidelink data. 30.The apparatus of claim 25, wherein, when the apparatus receives thesidelink data in consecutive slots, the one or more AGC symbols arereceived in only a first one of the consecutive slots.